Recently, disposable food containers are widely used in daily life and they are discarded after use. Some of the disposable containers used as bowls or cups are usually made of plastic material, such as expandable polystyrene, polypropylene or polyester foam. However, the disposable containers made of plastic material have a multitude of disadvantages. A major drawback of the disposable containers made of the plastic material is that it is not biodegradable and will exist for hundreds of years. Further, the disposable containers made of plastic material produce toxic gas when heated or burned, which causes air-pollution.
As a result, efforts have been made to develop biodegradable containers. Some prior art suggests using paper or starch to manufacture food containers. The use of paper as the raw material for food container is not a good choice, for paper is generally made from wood, pulp and woods are decreasing dramatically recently. Starch extracted form rice, wheat, potatoes or corns is a suitable material for the manufacturing of food containers. However, starch may serve as food for human being and other animals and is expensive. The manufacturing cost for the starch container is high and therefore cannot be widely used.
For solving the above problems, a method for manufacturing food containers is disclosed in Japanese Patent Application No. 6-259384. The method of Japanese Patent Application No. 6-259384 comprises the steps of (1) the husks are ground into powder or granular shape; (2) the husks are mixed with a cashew paint; (3) the mixture of the husks and the cashew paint is put. on a mold and then molded by means of adding on pressure through high temperature; and (4) a water-resistant paint is coated on the surface of the modeled container. However, the ratio of the husks and the cashew paint in the method of Japanese Patent No. 8-91340 is not defined clearly so that variations in the content of the husks and cashew paint may cause a variation of the quality of containers and the rate of degraded product may be increased which leads to an increase of the manufacturing cost
Further, a method for making disposable bowls and trays is disclosed in U.S. Pat. No. 5,500,089. The method of U.S. Pat. No. 5,500,089 comprises a multitude of steps and two of the steps are that the dried fiber sections are added to a container of starch paste containing water and then the dried fiber sections and starch paste are mixed to form mixed fiber and starch. However, the ratio of the dried fiber sections, starch paste and water is also not defined clearly in the two steps so that variations in the content of dried fiber sections, starch paste and water may also cause a variation of the quality of containers and the rate of degraded product may be increased which leads to an increase of the manufacturing cost.
Thus, it is desirable to have a method for manufacturing food containers to overcome above problems.